How to Implement Birthday Attack in NS2

 

To implement the birthday attacks in Network Simulator 2 (ns2), this attack is a variant of cryptographic attack that manipulates the mathematics behind the birthday paradox to discover hash collisions in cryptographic functions. The ns2 is mainly intended on network simulation so, ns2 does not support cryptography directly because it is not inherently developed for cryptography simulations.

Though, we can replicate the network characteristics of a birthday attack with an attacker may exploit hash collisions for things such as packet validation, session management or other cryptographic functions inside the networked scenarios. Since the ns2 can’t offer built-in functionalities to replicate cryptographic attacks, you can theoretically model the network activities during these attacks.

In the following, you can see how you could approach simulating a birthday-like attack scenario in NS2:

Conceptual Steps for Simulating a Birthday Attack in NS2:

  1. Simulate Data Transmission with Hash-Based Authentication:
    • Build an environment where nodes are interacting through the network, using hash-based packet validation (you can simulate this by attaching a pseudo-verification mechanism).
    • Each packet can have a distinct identifier (hash) that is validated at the receiver node.
  2. Introduce Malicious Nodes:
    • Malevolent nodes try to exploit the birthday paradox by generating hash collisions. These collisions can be imitated by having the malicious nodes send packets that have the same “hash” (or identifier) as legal packets leads to authentication issues.
  3. Monitor the Network Behavior:
    • Compute how the hash collisions impact the packet flow, authentication success, and how authorized nodes manage the attack.

As NS2 doesn’t simulate cryptographic functions like hashing, you can conceptually simulate hash collisions by deploying packet headers or identifiers. Below is an example of how this concept might be modeled in NS2.

Tcl Script for Simulating a Birthday Attack in NS2:

# Create a new simulator

set ns [new Simulator]

# Open trace file for output

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Define network nodes

set n0 [$ns node]  ;# Legitimate node 1 (Sender)

set n1 [$ns node]  ;# Legitimate node 2 (Receiver)

set n2 [$ns node]  ;# Malicious node (Attacker)

# Create duplex links between nodes

$ns duplex-link $n0 $n1 1Mb 10ms DropTail

$ns duplex-link $n2 $n1 1Mb 10ms DropTail  ;# Malicious node connected to the receiver

# Define TCP agents for legitimate communication between n0 and n1

set tcp0 [new Agent/TCP]

set sink0 [new Agent/TCPSink]

$ns attach-agent $n0 $tcp0

$ns attach-agent $n1 $sink0

$ns connect $tcp0 $sink0

# Create a traffic source (FTP) for legitimate communication

set ftp0 [new Application/FTP]

$ftp0 attach-agent $tcp0

$ns at 1.0 “$ftp0 start”

# Configure the malicious node to simulate hash collision by mimicking legitimate packets

proc birthday_attack {attacker victim} {

global ns

set udp [new Agent/UDP]

$ns attach-agent $attacker $udp

set cbr [new Application/Traffic/CBR]

$cbr attach-agent $udp

$cbr set packetSize_ 512

$cbr set interval_ 0.5  ;# Sending packets at regular intervals

$ns at 2.0 “$cbr start”

puts “Birthday attack: Malicious node is sending packets with ‘colliding’ identifiers.”

}

# Start the birthday attack at the malicious node

$ns at 2.0 “birthday_attack $n2 $n1”

# Schedule the end of the simulation

$ns at 10.0 “finish”

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# Run the simulation

$ns run

Explanation of the Script:

  1. Nodes:
    • n0: Legitimate sender.
    • n1: Legitimate receiver.
    • n2: Malicious attacker node, which will try to deliver packets with hash collisions.
  2. Legitimate Communication:
    • A TCP connection is accomplished amongst n0 (sender) and n1 (receiver), with FTP used to produce authorized traffic.
  3. Simulating the Birthday Attack:
    • The malicious node n2 sends UDP packets to the receiver (n1) with a constant packet size and interval, replicating hash collisions by imitating the traffic from legal nodes.
    • The malicious node acts like it’s sending packets with the same identifiers (conceptual hash collision) to complicate the receiver.
  4. Traffic Analysis:
    • The trace file (out.tr) will capture all the packets sent and obtained by the nodes. Test the trace file to monitor the influence of the attack on the communication among n0 and n1.

Post-Simulation Analysis:

  1. Trace File Analysis:
    • Open the trace file (out.tr) and search for packet flows amongst the malicious node (n2) and the receiver (n1). You can see how many packets from n2 (attacker) were acknowledged by n1 (the victim).
    • Detect the “collisions” caused by the malicious node sending packets that the receiver might obscure with authorized traffic.
  2. Impact on Legitimate Traffic:
    • Observe how the authentic communication amidst n0 and n1 is influenced. Check for any delays, packet loss, or other issues caused by the attack.
  3. Visualization with NAM (Network Animator):
    • NAM is used to visualize the network and watch how the malicious node (n2) sends packets that intrude with the legalized communication among n0 and n1.

Extending the Simulation:

  • Multiple Attackers:
    • Include more malicious nodes to replicate a distributed attack where several nodes try to congest the authorized communication by delivering “colliding” packets.
  • Different Traffic Patterns:
    • Imitate various intensities and patterns of the attack by modifying the traffic generation pattern for the malicious node (using CBR, Poisson and so on).
  • Varying Hash Collision Probability:
    • You can fine-tune the rate at which the malicious node produces traffic to simulate changing probabilities of hash collisions, imitating the birthday paradox.

In this demonstration, we thoroughly learned the entire implementation of Birthday Attacks using ns2 tool with samples which makes you to understand more about this attack monitoring and how to detect them during the simulation process and how to extend them.

Birthday Attack using the NS2 tool projects are worked by us, so if you need customized research, hit up ns2project.com for tailored assistance. You’ll get top-notch implementation results with us!